1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, etc., and more specifically, to an image forming apparatus with a blade-shaped abutment member which includes an image carrying member having a photosensitive layer and a photosensitive layer carrying member carrying thereon the photosensitive layer, and in which a latent image is formed on the image carrying member in an image forming area thereof in accordance with image information and developed to provide a toner image, which is then transferred to a transfer material, whereupon the residual toner attached to the image carrying member is removed by the abutment member.
2. Description of the Related Art
FIG. 10 is a cross sectional view illustrating the relation between a cylindrical (drum-shaped) photoreceptor (cylindrical photoreceptor) and a cleaning part for removing the toner, which is not transferred but remains on the photoreceptor, from the photoreceptor, in an image forming apparatus such as a copying machine, etc., applying electrophotography. There are two types of cleaning parts, one using a cleaning blade and the other using a roller in the form a fur brush. Practically, the main stream of the cleaning parts is a technique of using a cleaning blade 81 as shown in FIG. 10 because it is at low costs, easy to design, excellent in the scraping function, and so on. A photoreceptor 70 in FIG. 10 is used for repeatedly performing the processes of charging, image exposure, development, transfer, cleaning, etc., while being rotated in a direction of an arrow RR. Among these processes, a cleaning part 80 is used for removing the toner remaining on the photoreceptor 70 after the transfer process, and plays an important role of forming a clear copy image.
In the example as described above, the cleaning part 80 uses a plate-like cleaning blade 81 for removing toner. In this case, the cleaning blade 81 is mounted in such a manner that one 81a of opposite edges 81a, 81b of one side of the cleaning blade 81 is in abutment with a surface of the photoreceptor 70. Thus, in the cross sectional view of FIG. 10, the cleaning blade 81 is mounted in such a manner that an angle xcfx86, which is formed between the cleaning blade 81 and the tangent line of the photoreceptor 70 at a location at which the cleaning blade 81 abuts against the photoreceptor 70, become an acute angle. This angle xcfx86 is set such that the toner, which remains on the photoreceptor 70 without being transferred, can be efficiently scraped off and dropped into a collection part 82 in opposition to the rotation of the photoreceptor 70 in the direction of the arrow RR.
The cleaning part of the above-mentioned known image forming apparatus has an excellent cleaning characteristic through the use of the cleaning blade, but is apt to produce a large friction between the cleaning blade and the photoreceptor. As a result, there would arise a problem that those portions of the cleaning blade 81 in the vicinity of edges 81a, 81b thereof which are in abutment with the photoreceptor 70 are easily inverted or turned over (hereinafter also referred to as curling) due to the large friction, as shown in FIG. 11. Referring to FIG. 11, the portions of the cleaning blade 81 in the vicinity of the edges 81a, 81b thereof are turned over or curled up, so the edge 81b, instead of the edge 81a which has abutted against the photoreceptor 70 before occurrence of the turned-over or curling state, comes to be pressed against the surface of the photoreceptor 70, from which it will be understood that it is difficult to scrape off the toner remaining on the photoreceptor therefrom.
As a proposal for solving the problem of the known image forming apparatus as described above, there are inventions disclosed in Japanese Patent Application Laid-Open No. Hei 3-1979 and Japanese Patent Application Laid-Open No. Hei 7-319359 for instance. In the invention disclosed in Japanese Patent Application Laid-Open No. Hei 3-1979, the photoreceptor is prevented from being curled up by applying a lubricant such as an organic solvent dispersing liquid of lubricating minute powder such as Kynar, etc., to the surface of the photoreceptor at the initial stage of using the image forming apparatus. The lubricant is gradually removed from the photoreceptor as the operating time elapses, and does not serve for a lubricating function, but it is intended for toner to succeed the role of the lubricant in place thereof, thereby preventing curling of the photoreceptor.
In the above case, however, there is another problem in that if the lubricant, which is attached to the photoreceptor by application of the organic solvent dispersing liquid, is prevented from being detached from the photoreceptor so as to sustain the intended effect of the lubricant, an adverse influence resulting therefrom would appear to an image to be formed, giving rise to an image defect. Additionally, in this case, the photoreceptor includes an image forming area in which an image is formed according to image information. and a developing area which is wider than the image forming area and in which development is carried out by toner, and hence the toner used for development is supplied to the cleaning blade in a portion of the cleaning blade corresponding to the developing area, so that there would be little fear that a large friction might be generated between the cleaning blade and the photoreceptor. However, toner is not sufficiently supplied to the portions of the cleaning blade corresponding to those portions of the photoreceptor which lie outside the developing area thereof, thus causing a further problem that a large friction is created between the cleaning blade and the photoreceptor, from where the edges of the cleaning blade come to be easily turned over.
In the invention disclosed in Japanese Patent Application Laid-Open No. Hei 7-319359, there is proposed a technology of preventing the problem encountered with the above-mentioned invention, i.e., the turning over or curling in the portions of the cleaning blade, which lie outside the width of the developing area of the photoreceptor. In this proposal, development holding members are arranged at opposite ends of the cleaning blade, and intended to serve the purpose that the toner lying outside the width of developing area on a transfer belt is wiped off so as to adjust the toner to a suitable amount when the amount of toner is excessive, and the toner wiped off is made to attach to the transfer belt when the amount of toner lying outside the width of the developing area is too small, thereby making it possible to supply the toner to the entire surface of the cleaning blade. However, there arises a further problem that if non-image patterns continue at the opposite ends of the width of each image in the formation of images on the photoreceptor, toner would not be accumulated on the development holding members, thus resulting in a situation that there easily takes place curling of the cleaning blade.
The present invention is intended to solve the problems as referred to above, and has for its object to provide an image forming apparatus which is capable of preventing a cleaning blade from being curled up or turned over with the passage of an operation time thereof or due to the shapes of patterns forming images even when a cleaning blade, which is low in cost, easy to design and excellent in a toner scraping function, is used as a cleaning device.
In order to solve the above-mentioned problems, the present invention resides in an image forming apparatus which includes: an image carrying member (photoreceptor) having a photosensitive layer and a photosensitive layer carrying member (original pipe) carrying the photosensitive layer; a latent image forming device for forming a latent image on the image carrying member in accordance with image information; a developing device for forming a toner image on the latent image; a transfer device for transferring the toner image to a transfer material; and a cleaning device for removing a residual toner attached to the image carrying member by means of a blade-shaped abutment member (cleaning blade); and which is characterized in that a surface roughness of the photosensitive layer carrying member is greater outside the latent image forming area on the image carrying member than in the latent image forming area.
Moreover, the image forming apparatus according to the present invention is characterized in that concavities and convexities are provided on the photosensitive layer carrying member in a direction parallel to a direction in which the image carrying member rotates.
In addition, the image forming apparatus according to the present invention is characterized in that a surface roughness Rz outside the latent image forming area is 1.7-4.0 xcexcm.
Further, the image forming apparatus according to the present invention is characterized in that a range in which the surface roughness of the photosensitive layer carrying member is made greater is outside the latent image forming area and outside a location lying inside the developing area.
Furthermore, the image forming apparatus according to the present invention is characterized in that a range in which the surface roughness of the photosensitive layer carrying member is made greater is outside the developing area and outside a location lying inside the abutment member.
Still further, the image forming apparatus according to the present invention is characterized in that the image carrying member is cylindrical.
Besides, the image forming apparatus according to the present invention is characterized in that the image carrying member is of a belt-shaped configuration.
Moreover, the present invention resides in an image forming apparatus which includes: an image carrying member (photoreceptor) having a photosensitive layer and a photosensitive layer carrying member (original pipe) carrying the photosensitive layer; a latent image forming device for forming a latent image on the image carrying member in accordance with image information; a developing device for forming a toner image on the latent image; a transfer device for transferring the toner image to a transfer material; and a cleaning device for removing a residual toner attached to the image carrying member by means of a blade-shaped abutment member (cleaning blade); and which is characterized in that a lubricant having a friction against said abutment member smaller than that of the photosensitive layer is applied to the photosensitive layer carrying member outside the latent image forming area on the image carrying member.
In addition, the image forming apparatus according to the present invention is characterized in that a range in which the lubricant is applied is outside the latent image forming area and outside a location lying inside the developing area for forming the toner image,
Further, the image forming apparatus according to the present invention is characterized in that a range in which the lubricant is applied is outside the developing area and outside a location lying inside the abutment member.
Furthermore, the present invention resides in an image forming apparatus which includes: an image carrying member (photoreceptor) having a photosensitive layer and a photosensitive layer carrying member (original pipe) carrying the photosensitive layer; a latent image forming device for forming a latent image on the image carrying member in accordance with image information; a developing device for forming a toner image on the latent image; a transfer device for transferring the toner image to a transfer material; and a cleaning device for removing a residual toner attached to the image carrying member by means of a blade-shaped abutment member (cleaning blade); and which is characterized in that outside the latent image forming area on the image carrying member, the photosensitive layer is removed from the photosensitive layer carrying member, and a friction against the abutment member is smaller in the photosensitive layer carrying member than in the photosensitive layer.
Still further, the image forming apparatus according to the present invention is characterized in that a surface of the photosensitive layer carrying member is formed of an electroconductive fluorocarbon resin.
Besides, the image forming apparatus according to the present invention is characterized in that a range in which the photosensitive layer is removed is outside the latent image forming area and outside a location lying inside the developing area.
Moreover, the image forming apparatus according to the present invention is characterized in that a range in which the photosensitive layer is removed is outside the developing area and outside a location lying inside the abutment member.
In addition, the present invention resides in an image forming apparatus which includes; an image carrying member (photoreceptor) having a photosensitive layer and a photosensitive layer carrying member (original pipe) carrying the photosensitive layer; a latent image forming device for forming a latent image on the image carrying member in accordance with image information; a developing device for forming a toner image on the latent image; an intermediate transfer device for transferring the toner image so as to temporarily carry it thereon; a transfer device for transferring the toner image on the intermediate transfer device to a transfer material; and an intermediate transfer cleaning device for removing a residual toner attached to the intermediate transfer device by means of a blade-shaped intermediate transfer abutment member (cleaning blade); and which is characterized in that a friction against the intermediate transfer abutment member is smaller in portions of the intermediate transfer device outside the latent image forming area than in a portion of the intermediate transfer device in the latent image forming area.
Further, the image forming apparatus according to the present invention is characterized in that a lubricant is applied to the portions of the intermediate transfer device outside the latent image forming area.
Furthermore, the present invention resides in an image forming apparatus which includes: an image carrying member (photoreceptor) having a photosensitive layer and a belt-shaped photosensitive layer carrying member carrying the photosensitive layer; a plurality of image carrying member tensioning shafts among which the image carrying member is arranged under tension; a latent image forming device for forming a latent image on the image carrying member in accordance with image information; a developing device for forming a toner image on the latent image; a transfer device for transferring the toner image to a transfer material; and a cleaning device for removing a residual toner attached to the image carrying member by means of a blade-shaped abutment member (cleaning blade); and which is characterized in that the abutment member is greater in width than the image carrying member, and is arranged in a position to clamp the image carrying member together with one of the image carrying member tensioning shafts; and a friction against the abutment member is smaller at least in a portion of the image carrying member tensioning shaft with which the abutment member is in direct contact than in the image carrying member.
Still further, the image forming apparatus according to the present invention is characterized in that a lubricant is applied to at least the portion of the image carrying member tensioning shaft with which the abutment member is in direct contact.
Moreover, the present invention resides in an image forming apparatus which includes: an image carrying member (photoreceptor) having a photosensitive layer and a photosensitive layer carrying member (original pipe) carrying the photosensitive layer; a latent image forming device for forming a latent image on the image carrying member in accordance with image information; a developing device for forming a toner image on the latent image; a transfer device for transferring the toner image to a transfer material; a transfer material conveying device (transfer belt) for conveying the transfer material to the transfer device while carrying the transfer material thereon; a plurality of transfer material conveying tensioning shafts among which the transfer material conveying device is arranged under tension; and a transfer material conveying cleaning device for removing a residual toner attached to the transfer material conveying device by means of a blade-shaped transfer material conveying abutment member (cleaning blade); and which is characterized in that the transfer material conveying abutment member is larger in width than the transfer material conveying device, and arranged in a position to clamp the image carrying member together with one of the transfer material conveying tensioning shafts; and a friction against the transfer material conveying abutment member is smaller at least in a portion of the transfer material conveying tensioning shaft with which the transfer material conveying abutment member is in direct contact than in the transfer material conveying device.
Additionally, the image forming apparatus according to the present invention is characterized in that a lubricant is applied to at least the portion of the transfer material conveying tensioning shaft with which the transfer material conveying abutment member is in direct contact.
According to the arrangements as described above, such processing as adversely affecting the formation of an image is not performed in the image forming area, so it is possible to form an excellent image. Outside the image forming area, however, processing for reducing a friction against a contacting cleaning blade is carried out, thus avoiding curling or turning over of portions of the cleaning blade near its ends, which would otherwise be liable to be caused. In addition, with such a construction, friction can be continuously reduced, thus making it possible to scrape off a residual toner on a photoreceptor in a stable manner for a long period of time.
The above and other objects, features and advantages of the present invention will become more readily apparent to those skilled in the art from the following detailed description of preferred embodiments of the present invention taken in conjunction with the accompanying drawings.